The inadequate treatment of municipal solid waste which is being put in landfills and the increasing addition of nondegradable materials, including plastics, to the municipal solid waste streams are combining to reduce drastically the number of landfills available and to increase the costs of municipal solid waste disposal. While the recycling of reusable components of the waste stream is desirable in many instances, there are some products which do not readily fit into this framework, e.g. disposable personal absorbents such as diapers and sanitary napkins, garbage bags, and numerous other products. The composting of non-recyclable solid waste is a recognized and growing method of reducing solid waste volume for landfilling and/or making a useful product from the waste to improve the fertility of fields and gardens. One of the limitations to marketing such compost is the visible contamination by undegraded plastic such as film and fiber fragments.
As related in the aforesaid parent applications, which are hereby specifically incorporated herein by reference, there was a desired to achieve several objectives, as follows:
1--to provide components which are useful in disposable products and which are degraded into less contaminating forms under the conditions typically existing in waste composting processes. These conditions may involve temperatures no higher than 70 C., and averaging more nearly 55-60 C., humid conditions as high as 100% relative humidity, and exposure times which range from two weeks to more than three months. PA1 2--to provide disposable components which will not only degrade aerobically/anaerobically in composting, but will continue to degrade in the soil or landfill. As long as water is present, they will continue to break down into low molecular weight fragments which can be ultimately biodegraded by microorganisms completely into biogas, biomass and liquid leachate, as for natural organics like wood. PA1 3--to provide novel polyesters for making the aforementioned fibers, films, coatings and nonwoven sheets of the polyesters, and disposable diapers containing the nonwoven sheets. PA1 4--to provide polyesters and derivative products which have low ingredient costs and yet provide strength and toughness properties adequate for end uses such as in disposable diapers. PA1 wherein about 5 to 40 mole % of R is selected from the group consisting of a chemical bond and one or more divalent, non-aromatic, C.sub.1 -C.sub.10 hydrocarbylene radicals, and the remainder of R is at least about 85 mole % p-phenylene radical, PA1 wherein G is about 1 to 30 mole % of a polyethylene ether radical selected from the group consisting of --(CH.sub.2).sub.2 --O--(CH.sub.2).sub.2 -- and --(CH.sub.2).sub.2 --O--(CH.sub.2).sub.2 --O--(CH.sub.2).sub.2 -- the remainder of G is a hydrocarbylene radical selected from the group consisting of --(CH.sub.2).sub.2 --, --(CH.sub.2).sub.3 --, and --(CH.sub.2).sub.4 -radicals, PA1 wherein Q is derived from an hydroxy acid of formula HO[--C(O)--Q--O--].sub.x H, where x is an integer, such hydroxy acid having a melting point at least 5 C. below its decomposition temperature, and is selected from the group consisting of a chemical bond and hydrocarbylene radicals, --(CH.sub.2).sub.n --, where n is an integer from 1 to 5,--C(R')H--, and --C(R')HCH.sub.2 --, wherein R' is selected from the group of --CH.sub.3 and --CH.sub.2 CH.sub.3, with the aforesaid hydroxy acids and polyhydroxy acids and copolyesters therefrom being more fully described in application Ser. No. 07/645,995, PA1 wherein the mole fraction "a" may be 0.6 to 1 and, correspondingly, mole fraction "b" may be 0 to 0.4, and PA1 wherein about 0.1 to about 2.5 mole % of the polymer contains alkali metal or alkaline earth metal sulfo groups, preferably as a sodium 5-sulfoisophthaloyl radical, especially about 1.5 to about 2 mole % of such groups.
Accordingly, as described therein, useful novel polyesters were provided and fibers, non-woven sheet, films and combinations thereof, and disposable diapers comprising such materials. Such polyesters are useful for some end uses, e.g., as described. It would, however, be desirable to provide additional degradable materials, having properties that may be better adapted for various end uses. In particular, it is desirable to provide additional polyesters that can be formed into films that have good toughness, with similar advantageous properties in many respects, and polyesters having good rates of hydrolysis.
Abbreviations and nomenclature herein, except as otherwise indicated, are as described in aforesaid U.S. Pat. No. 5,053,482, and Applications Ser. Nos. 07/645,849 and 07/645,995, mentioned above, and pending applications Ser. Nos. 07/769,417 and 07/771,019 filed Oct. 1, 1991, all of which are hereby incorporated herein by reference, as are applications Ser. Nos. 834,795, 834,796, 834,793, 834,791, 834,792 and 834,797, being filed at the present time.